Unfortunately I can’t push to any repo from my machine. When I try to SSH to Gitlab instance it says “Welcome to GitLab, Anonymous!”, I’ve tried it from other machine and it says “Welcome to GitLab @username”

No, except from upgrading the GitLab I wasn’t changing nothing. I think it might be the issue with AWS configuration as the GitLab instance sits in AWS, but it works from the other machine within the same network which is really confusing.

We’re seeing the exact same problem. In our case, we have a single deploy key that is marked as write-activated, used in 23 of our projects. In the authorized_keys file, I do not see the deploy keys in the authorized_keys folder. The last thing I want to do is completely remove all my SSH keys and re-add them, given how much automation we have in place.

We are seeing the same @ghost user in our commit history as well. It definitely seems like something changed with 12.4!

Edit:

I’m looking through the changelog, and I saw this note in 12.4.1:
Disallow unprivileged users from commenting on private repository commits.
Now, we’re running 12.4, but this instantly makes me wonder if my deploy key is considered an unprivileged user.

I also found a merge request that deals with deploy key write permission:GitLab

Continued from: https://gitlab.com/gitlab-org/gitlab-foss/merge_requests/24553 ## What does this MR do? Change the privilege level needed to toggle write permission to a project for a global shared deploy keys from administrator to...

I am not sure of the answer is correct, but that’s how I solved my issue.
Also I would like to mention that SSH key is set for the user and not for project so you will not need to re-add that to all 23 projects you have.